Magnetic blow-out device



July 29. 1924. I

' E. R. CARICHOFF MAGNETIC BLOW-OUT DEVICE Filed Nov. 2, 1920 m P 3% R. 2% vn M e w a V. ab

His Attor' nay.

Patented July 2 9, 1924.

UNITED STATES PATENT OFFICE.

EUGENE n. CARICHOFF, or SCHENECTADY, NEW YORK, ASSIGNOR T GENERAL ELECTRIC COMPANY.- A CORPORATION OF NEW YORK.

MAGNETIC BLOW-OUT DEVICE.

Application filed November T 0 all whom it may concern: Be it known that I, EUGENE R. Caurcnorr, a citizen of the United States, residing at Schenectady, county of Schenectady, State of New York, have invented certain new and useful Improvements in Magnetic Blow-Out Devices, of which the following is a specification.

My invention relates to improvements in electromagnetic switches, and in particular to magnetic blow-out devices for disrupting the arcs formed between the switch contacts. The customary magnetic blow-out device is provided with a blow-out coil which is in series with the switch contacts or one which is included in the circuit of the are after the contacts separate. One of the objects of my invention is to eliminate this separate blow-out coil, thereby simplifying the 2 switch construction and also reducing the cost of manufacture. My invention has a particular application in electromagnetic switches provided with an operating or controlling magnetic structure through which a magnetic flux passes during the opening of the switch and also after the switch contacts have opened. In carrying my invention into effect, I connect my blow-out device across the points on the magnetic structure of the switch between which there is a difference of magnetic potential. A particular application of my invention is found in electromagnetic switches of the series lock-out type which are provided with a magnetic structure which is energized during the opening of the switch and also after the switch has opened. Such switches are customarily provided with two air gaps in the magnetic circuit, one a closing gap and the other a holding-out gap, and in carrying my invention into" effect in a switch of this character I connect two magnetic members to the magnetic structure so as to provide a shunt path for the magnetic flux around the closing gap, the flux through this shunt path passing across the space in which the contacts separate so as to disrupt any arcs formed between the contacts. i For a vbetter understanding of my invention, reference is had to the accompanying drawings, in which I have shown my invention embodied in concrete form for purposes of illustration, and in which Fig. 1 shows a side view of a series coil electromagnetic switch of the lockout type having 2, 1920. Serial N0. 421,212.

a shunt controlling coil and a magnetic blow-out device connected across the closmg gap in the magnetic circuit; Fig. 2 is is a plan view of the same; and Fig. 3 is a detail for-the purpose of showing the closing and holding-out gaps in the magnetic shown my invention embodied in an electro-' magnetic switch of the series lock-out type, described and claimed in -a co-pending application in which I am a joint applicant with Benjamin W. Jones. This joint application is assigned to the same assignee as this application, and the serial number thereof is 421,290, filed November 2, 1920.

Referring to the drawings, the switch mechanism is mounted on a base 10 of slate or other suitable insulating material, and the movable switch member 11 in the form of a bell crank lever is pivoted at 12 to the member 13 which is a part of the magnetic structure of the switch. The wiping contact.finger 14 is pivotally mounted on the bell crank switch member 11 at 15, and a spring 16 is provided for the purpose of resiliently mounting the contact 14- so that the contact 14 will make a wiping engagement with the stationary contact 17 in closing, and when the contactor is closed there will be a spring pressure between the contacts. The bell crank 11 is pivotally connected at 18 to a plunger 19 which constitutes the movable member of the magnetic structure of the switch. This plunger 19 is constructed substantially as shown in Fig. 3 with a lower portion 20 of reduced cross-sectional area. A sleeve 21 of brass or other non-magnetic material surrounds the lower end 20 of reduced cross-section for the purpose of preventing the plunger from sticking to the adjustable sleeve 22 of magnetic material which surrounds the end 20 and the sleeve 21. This adjustable sleeve 22 is prefcrabl in the form of a hollow cylindrical externa ly threaded screw, and the slceveis provided with a knurled head 23, by means of which the sleeve may be adjusted in position with respect to the plunger 19 and the lower supporting member 24 of magnetic material. A closing air gap 25 is provided between the upper and enlarged end of the plunger 19 andthe upper member 26 of the support if the switch windings are deener gized, or if the series winding 31 which surrounds a portion of the plunger 19 and completely surrounds the holding-open gap 27 is energized above the calibrating point, or in case the direction of current in the series winding 31 is reversed with respect to the shunt winding 32.

T o the right of the series coil 31 and located between the members 24 and 26 of magnetic material is the shunt control coil 32. This shunt control coil is mounted on a core 33 of magnetic material and is clamped between the'members 2t and 26 by means of the bolt 34. I

The magnetic structure of the operatincr electromagnet of this switch is energized at all times while the switch is in operation, and I make use of the magnetic flux of this operating magnet to extinguish the arcs formed between switch contacts 14 and 17 when the switch is opened. The closing gap 25 is closed when the switch is closed, but there is a drop of magnetic potential across this gap at all times while the switch is opening and when'theswitch. is opened because of the flux set. up by the shunt coil 32. In carrying my invention into effect, I connect my improved magnetic blow-out device in shunt to this closing gap, the strip 37 of magnetic material being magnetically connected with the lower member 24, and the strip 38 of magnetic material being connected tothe upper member 26 of the magnetic structure of th switch. Connected to .the upper ends of the strips 37 and 38 are the plates and 36 of magnetic material which are disposed parallel to the plane of movement of the switch contacts, and which are adapted to support the arc chute 39 of refractory material in such a position that the arcs formed between the switch contacts will be caused to proceed upwardly from the contacts through the arc chute.

The operation of my invention is as fol-- plunger 19 will be magnetically saturated and an increased flux "will cross the holding-out gap 27 and exert a force which will oppose the pull exerted by the flux across the closing gap 25 to such an extent that the switch will remain in the open position. In case the current drops.

to the predetermined value, the switch will be closed by reason of the fact that the pull at the closing gap 25 predominates. The shunt winding 32 is energized at all times while the switch is in operation to set up a flux in the magnetic structure which has no tendency to hold the switclnopen, but which nevertheless exerts a force which will close the switch in case the current in the series coil 31 is at any value less than the previously mentioned predetermined value. This value is ordinarilytermed the calibrating value or lock-out value.

If after the switch is closed. the current in the series coil 31 is reversed due, for instance, to what is termed a pump back, the switch will automatically open at a certain value of the reverse current. This is due to the fact that the flux set up by the shunt coil 32 is opposing the flux set up by the series coil 31, and for the further reason that the series coil is setting up a pronounced force across the holding-open gap 27. The switch will therefore automatically open, and while it is opening there will be adrop of magnetic potential across the closing gap 25. By reason of the fact that the magnetic blow-out device is arranged in shunt to this closing gap, the magnetic flux set up by the shunt coil will be caused to proceed through a path comprising the strip 37, across the switch contacts 14 and 17 at right angles to their plane of movement. and through the strip 38. This flux, which is eli'ective as a magnetic blow-out, will be effective even after the switch is open, and the arcs formed between the switch contacts are quickly disrupted and forced to proceed upwardly from the switch contacts through the arc Chute 39.

In accordance with the provisions of the patent statutes. I have described the principle of operation of my invention. together with the apparatus which I new consider to represent the best embodiment thereof. but I desire to have itnnderstood that the apparatus shown is only illustrative and that the invention can be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1.. An electromagnetic switch comprising an operating electromagnet having a magnetic structure with an air gap across which there is a difference of magnetic potential while the switch is opening, a pair of rela tively movable switch contacts, and a pair of magnetic members each of which has one end connected to the magnetic structure and the other end disposed adjacent the switch contacts, forming a path for the magnetic flux of the magnetic structure shunting the said air gap through which opened, a, pair of switch contacts operated by the said electromagnet to and from the closed position, and a magnetic blowout device adjacent the said contacts shunting the said gap. in the magnetic structure.

3. The combination with anelectromagnetic switch having relatively 'movable switch contacts and an operating electromagnet therefor having a magnetic structure through which a magnetic flux passes during the opening of the switch and after the switch is opened, of a magnetic blow-out device for disrupting the arcs formed between the switch contacts, comprising two members of magnetic material connected to points on the said magnetic structure between which there is a difference of magnetic potential.

4. The combination with an electromag- :netic switch having relatively movable switch contacts and an operating electromagnet therefor having a magnetic structure through which a magnetic flux passes during the opening of the switch and after the switch is opened, of a magnetic blowout device for disrupting the arcs formed between the switch contacts, comprising two members of-magnetic material connected to points on the said magnetic struc ture between which there is a difference of magnetic potential, and an arc chute through which the arcs formed between the contacts are adapted to pass supported between the said members.

5. The combination with an electromagnetic switch having relatively movable switch contacts and'an operating electromagnet therefor having a magnetic structure through which a magnetic flux passes during the opening of the switch and after the switch. is opened, of a magnetic blowout device for disrupting the arcs formed between the switch contacts, comprising a plurality of members of magnetic material connected to points on the said magnetic structure between which there is a difference of magnetic potential, and arranged to have corresponding ends of the members opposite each other adjacent the switch contacts so that the magnetic flux passing through the members passes at substantially right angles to the plane of movement of the switch contacts.

6. The combination with an electromagnetic switch having relatively movable switch contacts and an operating electromagnet therefor having a magnetic structure through which a magnetic flux passes during the opening of the switch and after the switch is opened, of a magnetic blowout device for disrupting the arcs formed between the said contacts comprising a plurality of members of magnetic material connected to 'points on the said magnetic structure between which there is a difference of magnetic potential, and arranged to have corresponding ends of the members opposite each other adjacent the switch contacts so that the magnetic flux passing through the members passes at substantially right angles to the plane of movement of the switch contacts arranged in shunt to the closing gap. 7

8. The combination in an electromagnetic switch of the lock-out type having a magnetic structure, a variable current winding, an operating member arranged between a closing air gap and a holding-open air gap in the magnetic structure, a constant current winding on the magnetic structure for setting up a flux across the closing gap,

and a magnetic blow-out device for the switch contacts energized by flux set up by the constant current winding.

9. The combination in. an electromagnetic switch of a switch operating member, an

operating electromagnet therefor having a variable current winding and a constant current winding normally supplementmg the effect of the variable current winding,

means whereby the said member is held in the open position when the current in the variable current winding is above a predetermined value and moves to the closed position when the current in the variable current winding drops to said value, and means whereby the arcs formed between the switch contacts when the switch opens are disrupted by the flux of the constant current winding.

10. The combination in an electromag netic switch of the lock-out type having a magnetic structure with a variable current winding and a constant current winding disposed thereon, a magnetic movable element under the control of said windings, a pair of relatively movable cooperating switch contacts magnetically held by the said magnetic element in the open position when the current in the Variable current winding is above a predetermined value, magnetically operated to the closed position when the current in the variable current winding drops to said value, and magneticall operated to the open position when the current in the Variable current winding reverses in direction, of a magnetic blow-out device comprising a plurality of members of magnetic material connected to the magnetic structure to be energized by the, said constant current Winding and arranged to have corresponding ends thereof adjacent the switch contacts so that the magnetic flux through the members is caused to be at substantially right angles to the plane of movement of the switch contacts EUGENE R. OARICHOFF. 

